does anyone get the front axle to 7825kg when loaded and the rear to 18192kg ? Would I be right to measure the wheelbase of a 3 axle rigid from between the lift and the drive ?
Edit , iam trying to get out of having super singles on the front uprating the steer axle to 9 tonne from 8 ,but unless every load is cemetrical or rear end heavy which they’re not then I have no choice . 
Punchy Dan:
Edit , iam trying to get out of having super singles on the front uprating the steer axle to 9 tonne from 8 ,but unless every load is cemetrical or rear end heavy which they’re not then I have no choice .
I think you’ve answered your own question there… 
You know your work better than anyone Punchy Dan, how often would you have to worry about a load that was front heavy which you’d have to ponce about with, or a couple of drops where once you got rid of one heavy lump you’d have to fully unchain, redistribute whats left, then chain down again.
You’ve got so little extra weight to play with on that steer axle that it would probably be quite a relief if you just bit the bullet and super singled up.
I suppose what iam asking is like the driver who asks will he get back home or turn in to pumpkin 
The theoretical wheelbase for a vehicle with unequally plated bogie axles is reached by dividing the plated weight of the lower plated axle by that of the higher and then multiplying by 100 to reach a percentage. The actual distance between axles 2 &3 is then multiplied by that percentage to arrive at the distance from lower plated axle to the theoretical centre line of the bogie. From that one can carry on with the moments calculations from the front axle to the theoretical wheelbase and load c/g.
Not as simple as that. Because you are using the load as a point load that is pretty much over the rear wheels you have all the load on the rear axles and none on the front.
You need to use formula for an evenly distributed load (if it is evenly distributed) and need to know the length of the load bed and the distances of the front and back of it from the axles.
Alternatively you could divide the load into a series of point loads along the load bed though you’d still need the length and position of the load bed. Would probably be easier than using uniformly distributed method though maybe not quite as accurate.
Edit, something like this.
Take moments about R1 to find R2 then take R2 away from WT to get R1 then add ULW for the front axle to get the total weight on the front axle.
Should be pretty accurate provided the load is evenly distributed and you have the correct point for R2 at the rear axles.
Thanks for replying all ,the load base( body) is 6.5m
What is the distance between centre line of axle 2 & of axle 3?
I’ll go measure , the other thing is IF I was to keep the 315s is there a aly wheel rated higher than 4150 kg and the highest rated 315 tyre I can find is continental at 4250 kg all the others are 4150kg
Distance between axle centres is 1.45m
cav551:
The theoretical wheelbase for a vehicle with unequally plated bogie axles is reached by dividing the plated weight of the lower plated axle by that of the higher and then multiplying by 100 to reach a percentage. The actual distance between axles 2 &3 is then multiplied by that percentage to arrive at the distance from lower plated axle to the theoretical centre line of the bogie. From that one can carry on with the moments calculations from the front axle to the theoretical wheelbase and load c/g.
Is the measurement not worked out as a percentage of the total
i.e. 11,500 & 7,500kg would be 11500/19000 = 60.5%
you are saying 7500/11500 = 65.2%
Based on midpoint of axles being 5950 behind front axles
Centre of load being 5900 behind front axle
With your method
effective centre of rear axles 5729 behind front axle
Giving axle weights of 7418 / 12118 / 6466
With my method
effective centre of rear axles 5748 behind front axle
Giving axle weights of 7452 / 11221 / 7326
I take it I am wrong, but why ?
No sorry my mistake you are right. But 60.5% of 1450 is not giving me 5748 as the distance from axle 1 so I am doing something else wrongly which I can’t get my head around. I assume from the diagram that the payload centre line or c of g is 60mm behind the true bogie centre line.
cav551:
No sorry my mistake you are right. But 60.5% of 1450 is not giving me 5748 as the distance from axle 1 so I am doing something else wrongly which I can’t get my head around. I assume from the diagram that the payload centre line or c of g is 60mm behind the true bogie centre line.
yes my 5748 is wrong. the 60.5% puts the effective centre 152mm in front of the real centre of 5950 which gives 5798 (i had took the 152 off the 5900)
so we now have 180kg coming off the front axle
so from front to back I now have 7540 / 11167 / 7292
Yes, Punchy Dans figures are confusing, i think they are a mad mix of Metres, cm and mm, he should have included some feet and inches for good measure 
he gives 'front load base as 590 (I have guessed this as 5900mm)
rear Load base of 0.06 (which I take it as meaning 60mm)
Wheelbase of 5.95 (which I take it as 5950mm from front axle to midway between the rear two axles)
(I ignored his 60mm as it conflicted with the other measurements)
It is more interesting than doing yet another suduko 
I’m really not trying to be a smart arse here, but what about using an eight legger. I’ve got me tin hat on cos I realise that’s an expensive way to go.
Have you asked dozy
Dan,
I was going to order a 6 wheel hook loader and needed a 9 ton front axle but did not want super singles on steer,I could keep the 315’s but they had to have a load rating of 160 (4,500kgs) at least to get to 9 ton, I’m looking for the quote now as it will have the tyre size etc on it, alternatively slide the hook back 6 inches?
Making it a 8 wheeler was something I thought about ,my cousins did make a fare few units in to 8 wheelers which are still in use today .
will I need spatz or should I be exempt being a hook loader ,the tyre is not quite out ,but the bulge is .